1. Field of the Invention
The invention relates to an endless V belt intended more particularly, but not exclusively, for equipping grooved pulley speed variators, or clutch devices for the motor car industry.
The invention relates more particularly to such an endless V belt of the type having a longitudinal reinforcement formed by a tension resistant member or several such members, such as cables, made for example from metal, glass fibers or any synthetic material having high tensile strength and transverse elements made from metal or another material having compression resistance, with an elastomer mass which joins the transverse elements solidly together and with the longitudinal reinforcement.
2. Description of the Prior Art
When such a belt is used as power transmission belt, for example in a speed variator it is subjected to high lateral compression forces exerted by the cheeks of the pulleys with which it cooperates and, in a belt of this type such as divulged by FR-A-2 452 035, i.e. in which the transverse elements are plates with a solid base and lateral fins, the curve representative of the bearing reactions of the cheeks of the pulleys on the plate is highly asymmetric. Such asymmetry of the bearing reactions, due to different stiffnesses of the base and of the fins of the plate results in lateral friction forces on the sides of the plates, proportional to the bearing reaction forces and, consequently, the driving forces of the belt which result from the friction forces also have an asymmetric distribution with respect to the reinforcement formed by a bundle of cables. With the barycenter thus removed from the center of application of the tractive force of said cables, in a direction perpendicular to that of the tractive force, a parasite moment tends to tip the plates over and introduce an effect harmful to the correct operation of the belt. The lifespan of this latter is then very considerably less than that which might be expected in most of the mechanisms which it equips, particularly speed variators.
The purpose of the invention is consequently to provide an improved V belt of the above mentioned type whose lifespan is considerably greater than that of the best known belts recommended in the prior art.